“Could Not Open Physical Device” in AS SSD Benchmark — What It Means and How to Fix It

You select your SSD, press Start, and instead of a benchmark you get a short message: “Could not open physical device.” Nothing is measured, no score appears, and the program gives you almost no extra detail. This guide explains what that message actually means, why it was a known bug in older builds, and the safe order in which to check your system — starting with your version number, not with system changes.

Before you start: back up important files on the drive you are troubleshooting. Most checks below are read-only, but the fixes that touch BIOS settings, partitions or drivers should never be attempted without a current backup.

What the message means

AS SSD Benchmark does not only read files on a volume. To measure sequential, 4K and access-time performance without the operating system cache distorting the result, it needs direct, low-level access to the physical drive behind the drive letter you selected. “Could not open physical device” means Windows refused that access, or the program failed while trying to obtain it. The drive itself is not automatically faulty — in most cases the block happens at the permission, driver or software level before any test data is written.

That distinction matters. A failed open is not a bad score and it is not a health verdict. AS SSD Benchmark has no SMART, health or temperature features, so this message tells you nothing about wear or remaining life. It only tells you the test could not start in the way the program needs. Treat it as an access problem first, and only consider hardware after the software causes below have been ruled out.

First check: are you on the final version?

Before changing anything, confirm which build you are running. The current and final version is 2.0.7316.34247, built in January 2020. According to the version notes recorded by Softpedia, the one confirmed change in that final build is exactly this point: Bugfix “Could not open physical device.” In other words, if you are running an older 2.0 or 1.x build, this error may simply be the old bug, and updating is the correct first fix — not a registry edit or a driver change.

If your copy came from an old download folder, a forum attachment or a software archive, replace it with a fresh copy from the official file. Our download page links to the official alex-is.de file and lists the verified SHA-256 hash so you can confirm the package is intact. Extract the ZIP fully before running it, and keep the AS SSD Benchmark.exe file together with its en-US language folder in the same directory — running the exe alone from inside the ZIP or from a different folder causes separate startup problems covered in our guide to AS SSD Benchmark not starting.

Back up first, then work through the access checks

Benchmarking is normally non-destructive, but troubleshooting is not the moment to take chances. Back up anything important on the drive before you start changing permissions, drivers or controller settings. Then work through these checks in order, retesting after each one rather than changing several things at once.

• Run as administrator.
• Close AS SSD Benchmark completely, right-click the exe and choose Run as administrator. Direct device access is exactly the kind of operation Windows may deny to a standard session, and this single step resolves many cases.
• Close other disk tools.
• Quit drive utilities, cloning tools, backup jobs and other benchmarks that may be holding the drive open, then try again. A drive that is actively being imaged or scanned may refuse a second low-level handle.
• Check security software.
• Antivirus and endpoint tools sometimes block direct disk access by unfamiliar portable programs. Note any prompt or log entry instead of disabling protection wholesale; if your security tool offers an allow prompt, use it only for the verified official file.
• Confirm the drive is online.
• Open Windows Disk Management and make sure the disk and volume show as online and healthy there. If Windows itself cannot open the volume normally, fix that first — AS SSD Benchmark will not succeed where the operating system is already struggling.
• Try a different target.
• If the program offers another connected drive, run a short test on that drive. If the other drive works, the problem is specific to the first drive, its driver or its connection. If no drive works, the problem is more likely permissions or the program copy itself.

Controller mode and driver context

Look at the top of the AS SSD Benchmark window once it opens. That area shows the drive model, firmware, controller information and partition alignment status — the same area behind warnings such as pciide – BAD. The display does not cause the open error, but it is useful context: a very old storage driver, an unusual RAID or virtual-disk arrangement, or a drive presented through a USB bridge can all change how direct access behaves. For background on those top-line labels, see our guide to checking AHCI vs IDE mode and the companion fix for pciide – BAD. Do not switch controller modes just to chase this error — mode changes carry a real boot risk and are covered, with warnings, in that pciide guide.

Also be honest about the environment. AS SSD Benchmark is a Windows desktop tool from 2020. Running it inside a virtual machine, through a remote session with restricted device access, or against a network or virtual disk may fail simply because the “physical device” the program expects is not exposed in the usual way. That outcome has not been separately verified for every hypervisor or configuration, so treat VM results as “test it on your setup” rather than as a guaranteed yes or no.

What not to do

Do not download “fixed” executables from random forums, do not replace system storage drivers with packages meant for a different chipset, and do not edit the registry on the strength of an old forum post without understanding exactly which key is involved and how to reverse it. Storage-driver and registry mistakes are one of the few ways a simple benchmark problem can turn into a system that no longer boots. Every step in this guide is reversible; keep it that way.

Equally, do not keep re-running the test dozens of times hoping it will pass. If the error is consistent after the version check, the administrator test and the close-other-tools test, you have useful information: the block is systematic. Note the exact version, the drive model shown in the window, and what you already tried — that record is worth more than another ten attempts.

When the drive itself becomes the suspect

Suspect the drive or its connection only after the software path is clean: final version, administrator session, no competing disk tool, and the drive visible and usable in Windows. Then check the basics — reseat or replace a SATA data cable where practical, try a different SATA port, and confirm the drive works normally for ordinary file copies. If Windows itself reports errors reading the drive, back up immediately and stop benchmarking: repeated full tests add load to a drive you may need for recovery.

If the drive is old, small or already showing problems in everyday use, a new SSD may be the practical answer — but use the error as a prompt to verify, not as proof. Once access works again you can benchmark the replacement properly and, if you are moving an existing Windows install, follow a careful cloning workflow rather than copying files by hand. Start from a clean, verified copy of the tool, work the checks in order, and this historically buggy error is usually either gone with the final version or explained by a permission you can fix in minutes.